President Donald Trump on Friday accelerated a long-anticipated shake-up of his Cabinet in the wake of the midterm elections, naming new picks for attorney general and U.N. ambassador amid widespread speculation that embattled White House Chief of Staff John Kelly could soon depart.

Trump confirmed his choices of William Barr to lead the Justice Department and Heather Nauert for the United Nations post as he left the White House, speaking to reporters over the din of the whirring blades of Marine One.

If confirmed by the Senate, Barr will take over for acting attorney general Matthew Whitaker. An unfettered Trump installed him in place of the ousted Jeff Sessions less than 24 hours after the polls closed on Nov. 6 in the first move of an expected overhaul of Cabinet secretaries and senior White House aides.

CNN reported Friday morning that Kelly could be stepping down in a matter of days, but Trump did not pause long enough to take questions from reporters, though he teased he would make another big personnel announcement Saturday at the Army-Navy game in Philadelphia.

"I can give you a little hint: It will have to do with the Joint Chiefs of Staff and succession," Trump said.

The Washington Post reported later Friday that individuals familiar with White House plans said Trump is expected to choose Gen. Mark Milley, the head of the Army, to become next chairman of the Joint Chiefs of Staff.

If his nomination is approved, Milley will replace the current chairman, Gen. Joseph Dunford Jr., who is due to step down next fall.

Kelly was not at work Friday morning, though an ally said he was simply taking a day off and would be at the White House for a holiday staff dinner Friday night. The lights were off in his West Wing office.

He has not been asked to resign, this person said, speaking on the condition of anonymity to speak candidly about a personnel matter.

Among White House officials, however, there is broad consensus that his days as chief of staff are numbered.

One senior administration official said Friday that it's clear Kelly will be leaving, though it's not certain that the departure was imminent as CNN reported. The official spoke on the condition of anonymity to discuss a sensitive matter.

Trump has engaged in talks with Nick Ayers, the vice president's chief of staff, about taking over the position, advisers said. The president often remarks on Kelly's lack of political skills and has told advisers in recent days that he needs a more political chief of staff for his reelection. Ayers, a sharp-elbowed and ambitious Georgia operative, fits the bill, advisers said.

But the story line of Kelly's departure has been protracted for so many months that White House aides often now just shrug.

"Sure, Trump says he wants him gone, and Kelly swears and leaves and says he's not coming back. But then he comes back," said one former senior administration official, who spoke on the condition of anonymity to offer a candid assessment.

Kelly, a retired four-star Marine general, has been the president's top aide since late July 2017. Trump has chafed at Kelly's management style and resisted some of his moves to instill discipline in the West Wing and contain chaos. In recent months, the chief of staff's power has ebbed, with administration policies and decisions being guided more by the president's gut instincts than by Kelly's processes.

Washington has been abuzz with rumors about Kelly's job status at various moments during his 16-month tenure. But this past summer, Kelly sought to quiet speculation that he was nearing the exit because of tensions with Trump by telling senior staff that he intended to remain as chief of staff through Trump's 2020 reelection campaign.

Trump and Kelly have privately argued at times and complained about each other to confidants, sometimes in colorful language. But the two men are generational peers and have a measure of respect for each other, and they have bonded over their shared ideology, especially on immigration issues, and their mutual grievances toward the media and political establishment.

Trump has long admired Kelly for his military valor, but his lack of political experience and interest in campaign strategy has made him an imperfect fit leading the staff of a president who lives and breathes politics. As Trump prepares for his 2020 reelection campaign, some advisers have counseled him to replace Kelly with a sharper operative who can steer the administration through the daily - and hourly - political fights sure to come.

Trump had nothing but praise for the two new Cabinet members who he announced Friday he would nominate.

He told reporters that Barr, who led the Justice Department under former president George H.W. Bush, was "my first choice since day one" and said he is "a terrific man, a terrific person, a brilliant man."

Nauert, 48, joined the State Department last year with no government experience after a career as an anchor and correspondent at Fox News.

"She's very talented, very smart, very quick, and I think she's going to be respected by all," Trump said.

Both the attorney general and U.N. ambassador positions require Senate confirmation. Aides on the Senate Foreign Relations and Judiciary committees - which would take up the ambassador and attorney general nominations, respectively - said Friday that neither committee will hold confirmation hearings this year, given the limited time left before a new Senate takes over on Jan. 3.

Barr is likely to face tough questions at his confirmation hearing about how he will handle the ongoing special counsel investigation into possible coordination between the Trump campaign and Russia to influence the 2016 presidential election.